Interdisciplinary Materials Research
Research Experience for Undergraduates

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            “Artificial-cell” like nanostructures for biosensing and drug and 

                                          gene delivery applications 

                                                     Dr. Punit Kohli

Our research focuses on the design, synthesis and characterization of novel liposome nanostructures for biosensing and drug/gene delivery applications. These nanoassemblies are composed of bilayer monomers which after polymerization forms highly robust “cell-like” structures (~100 nm in diameter). Specifically, we utilize these polymerized liposomes for selective, sensitive and fast assays for the detection and monitoring of chemically and biologically analytes (antibodies, nucleic acids, enzymes etc.) and particles (bacteria, viruses, spores etc.). In this approach, the liposomes composed of polymerized bilayers, fluorophores (organic or quantum dots) and receptors (antibodies and nucleic acids) will be synthesized.

Figure 1. The proposed approach to the detection and sensing of a ligand based on FRET mechanism. The fluorescence emission is quenched in “Off” state, but the fluorescence intensity enhanced after ligand binds to its receptors tethered to bilayer vesicles. This is “On” state of the system.

The fluorophores are “reporters” that will “signal” the detection of an analyte. The sensing of a ligand is accomplished using an “Off-On” optical switching mechanism through Fluorescence Resonance Energy Transfer (FRET) mechanism. The “Off” state (low fluorescence intensity) indicates the absence of interaction between receptors and ligands whereas the “On” state (high fluorescence intensity) represents the interaction between analytes and receptors. In other words, the large increase in the fluorescence signals the detection of analytes. These nanostructures are also being investigated for drug and gene delivery applications because they have large interior volume that can be filled with drugs or genes and can be targeted to desired sites through directed interactions between receptors tethered on to liposomes and ligands of cells.

REU students working of this project will have a unique opportunity to work in a highly interdisciplinary and collaborative research at the interface of Bio/Nano technology. They will synthesize and characterize semiconductor quantum dots (composed of CdSe core and ZnS shell) and polymerized vesicles using state-of-the-art analytical techniques such as scanning and transmission electron microscopies, X-ray diffraction, and UV-Vis, mass and fluorescence spectroscopies. The students will also interact and collaborate with other members of our group. This research experience gained by students would help them expose and contribute to solve complex scientific and technological problems in bio/nanotechnology and analytical and physical chemistries.